Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

An auto-document feeder includes a first image scanning section
configured to scan an image on first side of documents, a paper feeding
section configured to feed the documents one by one, from which images
are read by the first image scanning section, a paper discharge section
which discharges the documents passing through the first image scanning
section, plural conveying sections having different paths to reach the
first image scanning section and which guide the document from the paper
feeding section to the first image scanning section, a gate section which
directs the documents fed by the paper feeding section to one of the
plural conveying sections, a second image scanning section configured to
scan the image on second side of the documents, a double feeding
detecting section which positioned between the first image scanning
section and the second image scanning section.

Claims:

1. An auto-document feeder comprising: a first image scanning section
configured to scan an image on first side of a document; a paper feeding
section configured to feed documents one by one, from which images are
read by the first image scanning section; a paper discharge section which
discharges the documents passing through the first image scanning
section; plural conveying sections having different paths to reach the
first image scanning section and which guide the documents from the paper
feeding section to the first image scanning section; a gate section which
directs the documents fed by the paper feeding section to one of the
plural conveying sections; a second image scanning section configured to
scan the image on second side of the document; and a double feeding
detecting section positioned between the first image scanning section and
the second image scanning section.

2. The feeder according to claim 1, wherein the plural conveying sections
include a first conveying section and second conveying section, and the
gate section directs the documents from the paper feeding section to one
of the first conveying section and second conveying section in order.

3. The feeder according to claim 2, wherein the gate section alternately
directs the documents to the first conveying section or the second
conveying section.

4. The feeder according to claim 2, wherein the first conveying section
or second conveying section causes a following document to remain idle in
the conveying section while a preceding document is scanned by the image
scanning section.

5. The feeder according to claim 2, wherein the first conveying section
or second conveying section causes a time when a rear end of the
preceding document passes the image scanning member and a time when a
forward end of the following document reaches the image scanning section
to coincide with each other.

6. The feeder according to claim 2, wherein the first conveying section
has a first timing sensor which detects the documents and the second
conveying section has a second timing sensor which detects the documents.

7. The feeder according to claim 6, wherein the first conveying section
or the second conveying section detects a time when the rear end of the
preceding document passes the image scanning section by using the first
timing sensor or the second timing sensor, detects a time when the
forward end of the following document reaches the image scanning section
by using the first timing sensor or the second timing sensor, and causes
the time when the rear end of the preceding document passes the image
scanning section and the time when the forward end of the following
document reaches the image scanning section to coincide with each other.

9. A document feeding method comprising: directing documents to plural
conveying sections; conveying the documents directed to the plural
conveying sections to a first image scanning section configured to scan
an image of a first side of the documents continuously, in order;
detecting double feeding of the documents while scanning the image of a
first side of the documents; resolving double feeding when detecting
double feeding; and conveying the documents passing through a detecting
section to a second image scanning section configured to scan the image
of a second side of the documents.

10. The feeder according to claim 9, if the double feeding section
detects double feeding of the documents, conveying the document to the
first image scanning section after the double feeding is resolved.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based upon and claims the benefit of priority
from U.S. Provisional Application Ser. No. 61/476,536 filed on Apr. 18,
2011, the entire contents of which are incorporated herein by reference.

FIELD

[0002] This disclosure relates to an auto document feeding device which
conveys a document to an image scanning device used for a copy machine,
printer or the like that facilitates fast scanning.

BACKGROUND

[0003] In an image scanning device such as a scanner used for an image
forming apparatus such as a copy machine or printer, an increase in the
image scanning speed is desired. Conventionally, there is a device in
which plural document scanning conveying paths are formed and in which a
scanning sensor for scanning a face-side image of the document and a
scanning sensor for scanning a back-side image are provided in each
conveying path, respectively, thereby increasing the scanning speed at
the time of double-side scanning of the document images. As such an image
scanning device, for example, a device has a first branch path through
which a document is conveyed to a first scanning position, and a second
branch path through which a document is conveyed to a second scanning
position. Moreover, for example, a device can have a scanner device and a
CIS (contact image sensor) provided on the opposite sides of a first
conveying path and simultaneously uses the scanner device and the CIS to
scan both sides of a document conveyed on the first conveying path.

DESCRIPTION OF THE DRAWINGS

[0004] FIG. 1 is a configuration view schematically showing an image
scanning device according to an embodiment;

[0005] FIG. 2 is a block diagram showing a control system of an ADF
according to an embodiment;

[0006] FIG. 3 is a flowchart showing operations from turning on power to
starting supply of a document according to an embodiment;

[0007]FIG. 4 is a flowchart showing operations to supply the document and
convey the document to an OUT conveying member according to an
embodiment;

[0008] FIG. 5 is a flowchart showing an operation to convey the document
by using OUT conveying member according to an embodiment;

[0009] FIG. 6 is a flowchart showing operations from the start of scanning
of an image to the end of scanning;

[0010] FIG. 7 is a flowchart showing an operation to convey a following
document by using an IN conveying member according to an embodiment; and

[0011] FIG. 8 is a flowchart showing completion of the conveying according
to an embodiment; and

[0012] FIG. 9 is an explanatory view showing the distance between the
first sheet and the second sheet of the document according to an
embodiment.

DETAILED DESCRIPTION

[0013] According to an embodiment, an auto-document feeder includes a
first image scanning section configured to scan an image on first side of
a document; a paper feeding section configured to feed documents one by
one, from which images are read by the first image scanning section; a
paper discharge section which discharges the documents passing through
the first image scanning section, plural conveying sections which have
different paths to reach the first image scanning section and which guide
the documents from the paper feeding section to the first image scanning
section; a gate section which directs the documents fed by the paper
feeding section to one of the plural conveying sections; a second image
scanning section configured to scan the image on a second side of the
document; and a double feeding detecting section which is located between
the first image scanning section and the second image scanning section.

[0014] Hereinafter, an embodiment is described. FIG. 1 shows an image
scanning device 100 according to the embodiment. The image scanning
device 100 has a scanner 110, which is an image scanning member, and an
auto document feeding device (ADF) 10 which conveys a document G to the
scanner 110. The scanner 110 has a READ document glass 110a and a platen
glass 110b of a document setting table. The scanner 110 also has an
optical mechanism 110c. The optical mechanism 110c optically scans an
image of the document G traveling on the READ document glass 110a.
Alternatively, a driving unit moves the optical mechanism 110c in the
direction of arrow A (see FIG. 1), not shown, along the platen grass
110b, and optically scans the image of the document G set on the platen
glass 110b. The scanner 110 has a photosensor such as a CCD (charge
coupled device) 110d which photoelectrically converts an optical signal
from the optical mechanism 110c to an electric signal.

[0015] The auto document feeding device 10 has a document tray 11, which
is a document stacking member, a pickup roller 12 which takes out the
document G from the document tray 11, separation paper supply rollers 13
which prevent double feeding of two or more of the documents G, and
registration rollers 14 which align the forward end of the document G
removed and conveyed from the document tray 11. The auto document feeding
device 10 has two paths as conveying paths; namely, an OUT path 16 from
the registration rollers 14 to the scanner 110, and an IN path 17 from
the registration rollers 14 to the scanner 110. The OUT path 16, together
with the document tray 11, the pickup roller 12, the separation paper
supply roller 13, and the registration rollers 14, forms an OUT conveying
member 26, as a first conveying member, for example. The IN path 17,
together with the document tray 11, the pickup roller 12, the separation
paper supply rollers 13, and the registration rollers 14, forms an IN
conveying member 27, as a second conveying member, for example.

[0016] The OUT path 16 has intermediate OUT rollers 18. The IN path 17 has
intermediate IN rollers 28. The auto document feeding device 10 has a
gate 40 which directs the document G removed from the document tray 11
and passed through the registration rollers 14, to the OUT path 16 or the
IN path 17. The auto document feeding device 10 has pre-scan rollers 50
(upper pre-scan roller 50a, lower pre-scan roller 50b) which convey the
document G passed through the OUT path 16 or the IN path 17 to the READ
document glass 110a of the scanner 110; post-scan rollers 51 which
discharge the document G from the READ document glass 110a; pre-discharge
rollers 52; paper discharge rollers 53; and a paper discharge tray 56.
The post-scan rollers 51, the pre-discharge rollers 52, and the paper
discharge rollers 53 form a paper discharge member. A contact image
sensor (CIS) 60, which is a second image scanning member, is provided
between the post-scan rollers 51 and the pre-discharge rollers 52. The
contact image sensor (CIS) 60 can be provided in a conveying path
upstream of the paper discharge rollers 53.

[0017] On the READ document glass 110a, an image on the face side as a
first side of the traveling document G is scanned. The CIS 60 scans an
image on the back side as a second side of the traveling document G.
Thus, it is possible to scan the images on both sides of the document G
by passing the document once through the path.

[0018] An empty sensor 70 which detects the presence or absence of the
document G is provided above the document tray 11. A registration sensor
71 which detects arrival of the document Gat the registration rollers 14
is provided between the separation paper supply rollers 13 and the
registration rollers 14. In the OUT path 16, a paper timing sensor OUT 72
as a first timing sensor which detects the drive timing of the
registration rollers 14 and the intermediate OUT rollers 18 is provided.
In the IN path 17, a paper timing sensor IN 73 as a second timing sensor
which detects the drive timing of the registration rollers 14 and the
intermediate IN rollers 28 is provided.

[0019] A pre-scan sensor 76 and a double feed detection sensor 79 are
provided between the pre-scan rollers 50 and the READ document glass
110a. A scan sensor 77 is provided between the post-scan rollers 51 and
the pre-discharge rollers 52. A paper discharge sensor 78 is provided
between the pre-discharge rollers 52 and the paper discharge rollers 53.
Here, for example, the double feed detection sensor 79 is an ultrasonic
sensor.

[0020] A paper supply motor 80 drives the pickup roller 12 and the
separation paper supply rollers 13 to rotate. A pickup solenoid 81 causes
the pickup roller 12 to fluctuate. A registration motor (RGT motor) 82
drives the registration rollers 14 to rotate. The gate 40 is switched by
a gate solenoid 83. When the gate solenoid 83 is turned off, the gate 40
turns in the direction of arrow x and directs the document G to the OUT
conveying member 26. When the gate solenoid 83 is turned on, the gate 40
turns in the direction of arrow y and directs the document G to the IN
conveying member 27.

[0022] FIG. 2 shows a block diagram of a control system 120 suitable for
the ADF 10. The CCD 110d of the scanner 110 and the CIS 60 are connected
to a body control unit 121 which controls, for example, all or a part of
image forming apparatus having the image scanning device 100. The body
control unit 121 controls a CPU 130 of the ADF 10 via an input-output
interface 122. The empty sensor 70, the registration sensor 71, the paper
timing sensor OUT 72, the paper timing sensor IN 73, the pre-scan sensor
76, the scan sensor 77, the paper discharge sensor 78, and the double
feed detection sensor 79 are connected to the input side of the CPU 130.

[0023] The pickup solenoid 81, the paper supply motor 80, the RGT motor
82, the gate solenoid 83, the intermediate OUT motor 84, the intermediate
IN motor 86, the conveying motor 87, the upper READ motor 88a, the lower
READ motor 88b, and the paper discharge motor 89 are connected to the
output side of the CPU 130.

[0024] A process of continuously conveying the documents G is described
with reference to the flowcharts of FIG. 3 to FIG. 8. After power is
turned on, it is confirmed in ACT 200 that the ADF 10 is closed.
Detection is conveyed out at all the sensors in ACT 201 to confirm that
there is no jam of documents in the ADF 10 when closed. When the document
G is set on the document tray 11 in ACT 202, the empty sensor 70 turns on
and sends a document-on signal to the body control unit 121. After a
paper supply request signal is received from the body control unit 121 in
ACT 203, the processing goes to ACT 206.

[0025] In ACT 206, the pickup solenoid 81 is turned on and the paper
supply motor 80 is turned on to rotate the pickup roller 12 and the
separation paper supply rollers 13. Thus, supply of the document G1 as
the first sheet (the first document G1) is started. When the registration
sensor 71 turns on in ACT 207, the document G1 is conveyed for a
predetermined time and then the paper supply motor 80 is turned off and
the gate solenoid 83 is turned off (ACT 208). The first document G1 runs
into the registration rollers 14 and its forward end is aligned and then
the first document G1 stops. The gate 40 is set in the direction of
dividing the first document G1 to the OUT conveying member 26. If the
registration sensor 71 does not turn on even after the lapse of a
predetermined time in ACT 210, it is determined that the document G1
causes a jam.

[0026] When the registration sensor 71 turns on in ACT 207, the supply
process of the document G2 as the second sheet (the second document G2)
starts as an interruption process, separately from and parallel to the
conveying process of the first document G1. However, the supply process
of the second document G2 stands by or remains idle until the rear end of
the first document G1 passes through the registration sensor 71. After
the registration sensor 71 changes from on to off in ACT 300 (ACT 301),
the processing goes to ACT 206 and supply of the second document G2
starts.

[0027] After a predetermined time passes in ACT 211 and the document G1 is
a sheet of an odd ordinal number (ACT 212), the RGT motor 82 and the
intermediate OUT motor 84 are turned on to rotate the registration
rollers 14 and the intermediate OUT rollers 18 (ACT 214) respectively.
The intermediate OUT rollers 18 are adjusted to the rotation speed of the
registration rollers 14, and the registration rollers 14 and the
intermediate OUT rollers 18 are rotated at a uniform velocity. The first
document G1 is directed by the gate 40 and moves to the OUT conveying
member 26.

[0028] When the paper timing sensor OUT 72 turns on in ACT 215, the RGT
motor 82 and the intermediate OUT motor 84 are driven for a predetermined
number of pulses and then stopped (ACT 216). The first document G1 stops
before the pre-scan rollers 50. If the paper timing sensor OUT 72 does
not turn on even after the lapse of a predetermined time in ACT 217, it
is determined that the document G1 causes a jam.

[0029] After a conveying request signal is received from the body control
unit 121 in ACT 218, the processing goes to ACT 220. When the scanner 110
can scan, the body control unit 121 sends a conveying request signal to
the CPU 130. When there is a preceding document G, and when a
predetermined period of time passes after the forward end of the
preceding document G turns on the pre-scan sensor 76 (ACT 220), the
processing goes to ACT 221.

[0030] In ACT 221, the upper READ motor 88a, the lower READ motor 88b, the
conveying motor 87 and the intermediate OUT motor 84 are turned on to
rotate the intermediate OUT rollers 18, the pre-scan rollers 50, the
post-scan rollers 51, and the pre-discharge rollers 52 at a suitable
speed according to an instruction from the body control unit 121. The
time when the rear end of the preceding document G passes the pre-scan
rollers 50 and the time when the forward end of the first document G1
starts conveying by the pre-scan rollers 50 are caused to coincide with
each other. The first document G1 is conveyed to the READ document glass
110a in the state where the distance from the rear end of the preceding
document G is reduced and approaches 0 mm.

[0031] When the first document G1 is conveyed, the double feed detection
sensor 79 determines whether double feeding has taken place or not (ACT
230). The detected signal is sent to the body control unit 121. There are
two types of double feeding. The body control unit 121 determines whether
double feeding occurs when the document G1 is fed from the document tray
11 or whether double feeding occurs when there is overlap with a rear end
of the preceding document G (ACT 231). In the former case, the body
control unit reverses the upper READ motor 88a at predetermined time and
returns the document G1 which is double fed to the OUT conveying member
26(ACT 232). While return the document G1, the body control unit 121
rotates the lower READ motor 88b and continues scanning. After a
predetermined time has passed, the upper READ motor 88a rotates and
conveys a separated document. Here, when double feeding is detected,
after the upper READ motor 88a and the lower READ motor 88b are stopped,
the upper READ motor 88a reverses and returns the document which is
double fed to the OUT conveying member 26, the lower motor 88b can be
rotated and the document G can be conveyed to the READ document glass
110a.

[0032] Moreover, at the time of separation operation of double fed
document, the pre-scan roller 50 makes nip pressure of the pre-scan
roller 50 smaller than the time of conveyance according to the nip
adjustment mechanism is not illustrated.

[0033] When the double feeding involves overlapping with a rear end of the
preceding document G, the body control unit 121 stops the intermediate
OUT motor 84 (ACT 233). After predetermined time, the intermediate OUT
motor 84 is driven to re-convey the document G1. If double feeding is
canceled and the document G1 is conveyed by a predetermined distance (ACT
234), a scan start signal is sent to the body control unit 121.

[0034] The body control unit 121 causes the scanner 110 to start scanning
an image on the face side of the document G1 (ACT 235).

[0035] In parallel, when the rear end of the first document G1 passes
through the registration sensor 71 and the registration sensor 71 changes
from on to off, supply of the second document G2 is started in ACT 300.
The first document G1 travels on the READ document glass 110a. The
scanner 110 scans an image of the first document G1. The second document
G2 runs into the registration rollers 14 and its forward end is aligned.
And then the second document G2 stops.

[0036] To convey the second document G2 in parallel, when the registration
sensor 71 turns on (ACT 207), the processing reaches ACT 212 via ACT 208
and ACT 211. In ACT 212, if the document G2 is a sheet of an even ordinal
number, the processing goes to ACT 250. In ACT 250, the gate solenoid 83
is turned on and the gate 40 is thus switched to the direction to direct
the second document G2 to the IN conveying member 27. Then, in ACT 251,
the OGT motor 82 and the intermediate IN motor 86 are turned on to rotate
the registration rollers 14 and the intermediate IN rollers 28. The
intermediate IN rollers 28 are adjusted to the rotation speed of the
registration rollers 14, and the registration rollers 14 and the
intermediate IN rollers 28 are rotated at a uniform velocity. The second
document G2 is divided by the gate 40 and moves to the IN conveying
member 27.

[0037] In ACT 235, the first document G1 continues traveling on the READ
document glass 110a and the scanner 110 continues scanning the image. The
first document G1 is conveyed in the direction of the paper discharge
rollers 53 via the post-scan rollers 51 and the pre-discharge rollers 52.
When the first document G1 turns on the paper discharge sensor 78 (ACT
236), the paper discharge motor 89 is driven to rotate the paper
discharge rollers 53. In the case of double-side scan (Yes in ACT 238),
the processing goes to ACT 239. In ACT 239, an image on the back side of
the first document G1 conveyed in the paper discharge direction is
scanned by the CIS 60. When a predetermined time passes (ACT 240) after
the paper discharge sensor 78 is turned on, image scanning on the face
side of the first document G1 by the scanner 110 is finished (ACT 241).
After the rear end of the document is passed through the rollers 51, the
conveying motor 87, the upper READ motor 88a, the lower READ motor 88b,
and the intermediate OUT motor 84 are turned off (ACT 242).

[0038] In parallel, With respect to the second document G2, when the paper
timing sensor IN 73 is turned on in ACT 252, the RGT motor 82 and the
intermediate IN motor 86 are driven by a predetermined number of pulses
and then stopped (ACT 253). The second document G2 is stopped before the
pre-scan rollers 50 in the IN conveying member 27. If the paper timing
sensor IN 73 does not turn on even after a predetermined time passes in
ACT 254, it is determined that the document G1 causes a jam. After a
conveying request signal for the second document G2 is received from the
body control unit 121 in ACT 256, the processing goes to ACT 257.

[0039] When a predetermined time passes after the forward end of the
preceding document G (the first document S1) turns on the pre-scan sensor
76 in ACT 257, the processing goes to ACT 258. In ACT 258, the upper READ
motor 88a, the lower READ motor 88b and the intermediate IN motor 86 are
turned on and the intermediate IN rollers 28, the pre-scan rollers 50,
the post-scan rollers 51, and the paper discharge rollers 52 are rotated
at a suitable speed according to an instruction from the body control
unit 121. The time when the rear end of the preceding document G (the
first document G1) passes the pre-scan rollers 50 and the time when the
forward end of the second document G2 starts the conveying by the
pre-scan rollers 50 are caused to coincide with each other. The second
document G2 is conveyed to the READ document glass 110a in the state
where the distance between the rear end of the preceding document G (the
first document G1) and the forward end of the second document G2 is
minimized and approaches 0 mm.

[0040] To realize the state where the distance between the rear end of the
preceding document G (the first document G1) and the forward end of the
second document G2 is close to 0 mm, for example, the distance from the
paper timing sensor OUT 72 to the pre-scan rollers 50 and the distance
from the paper timing sensor IN 73 to the pre-scan rollers 50 are set to
be equal. After the paper timing sensor IN 73 is turned on, the second
document G2 waits at a position advanced by a predetermined distance.
When the rear end of the preceding document G (the first document G1)
passes through the paper timing sensor OUT 72 and advances by the
predetermined distance, the READ motor 87 and the intermediate IN motor
86 are turned on to convey the second document G2 in the direction of the
READ document glass 110a. Thus, the distance between the rear end of the
first document G1 and the forward end of the second document G2 can be
made close to 0 mm.

[0041] Alternatively, the timing of conveying the preceding document G1
(the first document G1) and the second document G2 can be adjusted in
advance in accordance with the result of detection by the paper timing
sensor OUT 72 and the result of detection by the paper timing sensor IN
73, thus realizing the state where the distance between the preceding
document G (the first document G1) and the second document G2 approaches
0 mm.

[0042] When the second document G2 is conveyed, the double feed detection
sensor 79 determines whether double feeding has occurred or not (ACT
230). If the second document G2 is double fed, double feeding is resolved
in the same way as the first document G1 (ACT 231, ACT 232, ACT 233).

[0043] The second document G2 conveyed to the READ document glass 110a
after the preceding document G (the first document G1) in ACT 258 is
conveyed by a predetermined distance (ACT 234) and then image scanning on
the face side by the scanner 110 is started (ACT 235). In parallel, when
the rear end of the second document G2 passes through the registration
sensor 71 and the registration sensor 71 changes from on to off, supply
of the document G3 as the third sheet (the third document G3) is started.
The first document G1 is discharged in the direction of the paper
discharge tray 56 by the paper discharge rollers 53. The second document
G2 travels on the READ document glass 110a. The third sheet of the third
document G3 runs into the registration rollers 14 and its forward end
position aligned. And then the third document G3 stops.

[0044] To convey the third sheet of the document G3 in parallel, as the
registration sensor 71 turns on (ACT207), the processing reaches ACT 212
via ACT 208 and ACT 211. In ACT 212, if the third document G3 is a sheet
of an odd ordinal number, the processing goes to ACT 214. In ACT 208, the
gate solenoid 83 is turned off and the gate 40 is switched in the
direction of directing the third document G3 to the OUT conveying member
26. In ACT 214, the registration rollers 14 and the intermediate OUT
rollers 18 are rotated to convey the third document G3 to the OUT
conveying member 26. The first document G1 is set on the paper discharge
tray 56. The second document G2 travels on the READ document glass 110a
and turns on the paper discharge sensor 78. The third document G3 stops
before the pre-scan rollers 50 in the OUT conveying member 26. After
that, the third document G3 is conveyed to the READ document glass 110a
in the state where the distance from the rear end of the preceding
document G (the second document G2) is reduced and approaches 0 mm.

[0045] When the document G is not the final document, ACTs 214 to 222
(conveying of the document G by the OUT conveying member 26) and ACTs 250
to 259 (conveying of the document G by the IN conveying member 27) are
alternately repeated and the documents are continuously conveyed in the
state where the distance between the preceding document and the following
document is close to 0 mm (ACT 260). When the document G is the final
document and the paper discharge sensor 78 turns off (ACT 261), the final
document is conveyed by a predetermined distance by the paper discharge
rollers 53 (ACT 262). All the motors and solenoids are turned off (ACT
263). Then, conveying of the document by the ADF 10 is completed.

[0046] According to this embodiment, in the case of continuously scanning
the documents G, two conveying members are used; namely, the OUT
conveying member 26 and the IN conveying member 27. While the preceding
first document G1 is conveyed by using one conveying member, the next
second document G2 remains idle in the other conveying member. The time
when the preceding first document G1 passes through the scanner 110 and
the time when the next second document G2 is conveyed to the scanner 110
are caused to coincide with each other. Thus, the documents G are
continuously conveyed in the state where the distance between the
preceding first document G1 and the next second document G2 is close to 0
mm.

[0047] While certain embodiments have been described, these embodiments
have been presented by way of example only, and are not intended to limit
the scope of the inventions. Indeed, the novel embodiments described
herein may be embodied in a variety of other forms; furthermore, various
omissions, substitutions and changes in the form of the embodiments
described herein may be made without departing from the spirit of the
inventions. The accompanying claims and their equivalents are intended to
cover such forms or modifications as would fall within the scope and
spirit of the inventions.